// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2017-2019 The WaykiChain Developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "sync.h"
#include "commons/util/util.h"
#include "logging.h"

#ifdef DEBUG_LOCKCONTENTION
void PrintLockContention(const char* pszName, const char* pszFile, int nLine)
{
    LogPrint(BCLog::INFO,"LOCKCONTENTION: %s\n", pszName);
    LogPrint(BCLog::INFO,"Locker: %s:%d\n", pszFile, nLine);
}
#endif /* DEBUG_LOCKCONTENTION */

#ifdef DEBUG_LOCKORDER
//
// Early deadlock detection.
// Problem being solved:
//    Thread 1 locks  A, then B, then C
//    Thread 2 locks  D, then C, then A
//     --> may result in deadlock between the two threads, depending on when they run.
// Solution implemented here:
// Keep track of pairs of locks: (A before B), (A before C), etc.
// Complain if any thread tries to lock in a different order.
//

struct CLockLocation
{
    CLockLocation(const char* pszName, const char* pszFile, int nLine)
    {
        mutexName = pszName;
        sourceFile = pszFile;
        sourceLine = nLine;
    }

    string ToString() const
    {
        return mutexName+"  "+sourceFile+":"+itostr(sourceLine);
    }

    string MutexName() const { return mutexName; }

private:
    string mutexName;
    string sourceFile;
    int sourceLine;
};

typedef vector< pair<void*, CLockLocation> > LockStack;

static boost::mutex dd_mutex;
static map<pair<void*, void*>, LockStack> lockorders;
static boost::thread_specific_ptr<LockStack> lockstack;


static void potential_deadlock_detected(const pair<void*, void*>& mismatch, const LockStack& s1, const LockStack& s2)
{
    LogPrint(BCLog::INFO,"POTENTIAL DEADLOCK DETECTED\n");
    LogPrint(BCLog::INFO,"Previous lock order was:\n");
    for (const auto& i : s2)
    {
        if (i.first == mismatch.first) LogPrint(BCLog::INFO," (1)");
        if (i.first == mismatch.second) LogPrint(BCLog::INFO," (2)");
        LogPrint(BCLog::INFO," %s\n", i.second.ToString());
    }
    LogPrint(BCLog::INFO,"Current lock order is:\n");
    for (const auto& i : s1)
    {
        if (i.first == mismatch.first) LogPrint(BCLog::INFO," (1)");
        if (i.first == mismatch.second) LogPrint(BCLog::INFO," (2)");
        LogPrint(BCLog::INFO," %s\n", i.second.ToString());
    }
}

static void push_lock(void* c, const CLockLocation& locklocation, bool fTry)
{
    if (lockstack.get() == NULL)
        lockstack.reset(new LockStack);

    LogPrint(BCLog::LOCK, "Locking: %s\n", locklocation.ToString());
    dd_mutex.lock();

    (*lockstack).push_back(make_pair(c, locklocation));

    if (!fTry) {
        for (const auto& i : (*lockstack)) {
            if (i.first == c) break;

            pair<void*, void*> p1 = make_pair(i.first, c);
            if (lockorders.count(p1))
                continue;
            lockorders[p1] = (*lockstack);

            pair<void*, void*> p2 = make_pair(c, i.first);
            if (lockorders.count(p2))
            {
                potential_deadlock_detected(p1, lockorders[p2], lockorders[p1]);
                break;
            }
        }
    }
    dd_mutex.unlock();
}

static void pop_lock()
{
    if (fDebug)
    {
        const CLockLocation& locklocation = (*lockstack).rbegin()->second;
        LogPrint(BCLog::LOCK, "Unlocked: %s\n", locklocation.ToString());
    }
    dd_mutex.lock();
    (*lockstack).pop_back();
    dd_mutex.unlock();
}

void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry)
{
    push_lock(cs, CLockLocation(pszName, pszFile, nLine), fTry);
}

void LeaveCritical()
{
    pop_lock();
}

string LocksHeld()
{
    string result;
    for (const auto&i : *lockstack)
        result += i.second.ToString() + string("\n");
    return result;
}

void AssertLockHeldInternal(const char *pszName, const char* pszFile, int nLine, void *cs)
{
    for (const auto&i : *lockstack)
        if (i.first == cs) return;
    fprintf(stderr, "Assertion failed: lock %s not held in %s:%i; locks held:\n%s",
            pszName, pszFile, nLine, LocksHeld().c_str());
    abort();
}

#endif /* DEBUG_LOCKORDER */
